Proudas - sorry you're going through this.
Stuff I do that helps (a bit and not always but can do):
Don't overdo it. Recognise you are ill so don't get angry that you are not up to doing as much as normal, or that you fall behind. Focus on what you are managing to do, however small those achievements might be.
Always give yourself a pat on the back for what you do manage to get done, however minor (there's a pat on the back thread on here somewhere.)
Make very short lists of stuff that needs doing - no more than 3 things - one of them easy. And when you've done them, give yourself a bit of time off for a coffee or a breather.
Remind yourself you don't have to want to do something or feel even a tiny bit enthusiastic about it to do it. I say this to myself every morning: just because you don't want to have a shower doesn't mean you won't have one. For some reason this works. Just because you don't want to write that difficult work email/go to your mate's party doesn't mean you won't do it.
When you fail to achieve stuff, forgive yourself. I had a meeting today and just didn't get all the work done for it. Was really unable to concentrate at the weekend when I should have been preparing for it. Instead of cancelling I went in and told them how far I'd got, gave feedback up to that point and a realistic time for finishing. Not ideal, but I didn't cringe and apologise or lie, just focused hard on what I had managed to do not what I hadn't.
Try to do something from the mood elevation list every day before or after work (put on happy music, watch happy comedies or romances, listen to funny radio shows, go for walks in the sunshine, do vigorous physical exercise, chat to a friend who tends to lift your spirits not whinge at you, meet someone face to face for coffee/walk/lunch/fun.) I do tiny mood lifting things like put on music I love or cuddle the cat/DC as the effort is small but the pay off is big.
I also find having quite a casual but combative attitude to the depression helps. When I don't want to do something I know I need to do and would feel better for having done, I tell the depression to fuck off for a moment while I do this. Doesn't yet work for more challenging tasks but helps stop me from totally giving up unless I'm having an exceptionally bad day.
All this is stuff I can do on ADs. Not suggesting any of this is much help or even possible if not on ADs.